Joomla! Update not available on 2.5.28 - Joomla! Forum - community, help and support

ok, i'm wanting upgrade 3.n. read instructions. everything's go. instructions @ https://docs.joomla.org/joomla_3_faq say;

once ready, go joomla! update component. click on options , change setting short term support. save. should notified of availability of joomla! 3.x. click button install. clear browser’s cache make sure see latest changes. that’s it!

unfortunately me, that's not "that's it!". don't see joomla! update on component menu. looking extensions > management "joomla! update", has lock icon next , cannot enabled. assuming that's component, of course?

any help, anyone?

download update package , install extensions installer.
http://joomlacode.org/gf/download/frsrelease/20020/162254/joomla_3.4.1-stable-update_package.zip

https://docs.joomla.org/upgrade_instructions#migration_2.5_to_3.x

does server meet minimum technical requirements?